(1) Field of the Invention
The invention relates to a method of removing an unnecessary matter such as a protective tape or a resist film from a surface of a semiconductor wafer by means of a separation tape.
(2) Description of the Related Art
In a fabrication process of a semiconductor wafer (hereinafter, simply referred to simply as “wafer”), at the time when a back face of the wafer, that has been previously patterned, is ground (back grinding), a wide protective tape is joined beforehand onto the wafer surface. The protective tape projected from an outer periphery of the wafer is cut out along an outer diameter of the wafer. The wafer with the whole surface thereof covered by the protective tape is suction-held by a sucker from the surface and, then, is subjected to a grinding process. After that, the protective tape necessary no longer is removed from the wafer surface.
A method of separating the protective tape uses a separation tape. According to this method, a separation tape having an adhesion higher than that of the protective tape is joined to the protective tape (unnecessary matter) on the wafer surface using a roller rolled thereon. After that, the separation tape is wound off, so that the protective tape is separated together with the separation tape. Upon separating and removing the unnecessary protective tape by the separation tape from the wafer thinned in the back grinding process, the separation tape cannot be joined up to the end of the protective tape and the protective tape cannot be separated in stable manner. In view of this, there has been proposed a method of separating and removing the protective tape using an edge member (JP-A 2002-124494).
In recent years, however, trend is an increased rate at which bumps are formed on the surface of the semiconductor chip. In the case where the protective tape is separated from the wafer formed with the bumps on the surface thereof by the method described in JP-A 2002-124494, the wafer surface may be damaged. Also, friction between the edge member and the separation tape may generate foreign matters. In view of this, the present inventor has made vigorous efforts to solve this problem by separating the protective tape with the edge member moved upward and has come to know the new problem that the protective tape is slid in a lateral direction immediately before leaving the wafer end and the adhesive surface of the protective tape rubs the wafer surface, with the result that the wafer surface is contaminated.